The accurate knowledge of the antenna factor is a fundamental requirement for reliable
electromagnetic compatibility (EMC) measurements in emissions, immunity and human exposure tests.
According to international standards, this would imply calibrating antennas in close-to-ideal test sites
(calibration test sites), characterized by very large sizes of the ground plane and of the empty space
volume above it (free-space behaviour). On the other hand the greater number of EMC test sites is
designed for measurements at 3 meters distance, therefore it would be very convenient to calibrate
antennas in such facilities at the cost of an acceptable loss of accuracy. In this paper, the authors
investigate on the suitability of compact (standard compliant for measurements at 3 m) semi-anechoic
rooms for reliable antenna factor calibrations of EMI antennas. As an example, the calibration of a
common broadband biconical antenna in the range 200 MHz-1 GHz has been considered. A detailed
experimental analysis was performed for estimating all the involved uncertainty components.

The accurate knowledge of the antenna factor is a fundamental requirement for reliable
electromagnetic compatibility (EMC) measurements in emissions, immunity and human exposure tests.
According to international standards, this would imply calibrating antennas in close-to-ideal test sites
(calibration test sites), characterized by very large sizes of the ground plane and of the empty space
volume above it (free-space behaviour). On the other hand the greater number of EMC test sites is
designed for measurements at 3 meters distance, therefore it would be very convenient to calibrate
antennas in such facilities at the cost of an acceptable loss of accuracy. In this paper, the authors
investigate on the suitability of compact (standard compliant for measurements at 3 m) semi-anechoic
rooms for reliable antenna factor calibrations of EMI antennas. As an example, the calibration of a
common broadband biconical antenna in the range 200 MHz-1 GHz has been considered. A detailed
experimental analysis was performed for estimating all the involved uncertainty components.